Keithley 3720 User Manual

Series 3700
System Switch/Multimeter User's Manual Section 5:
Basic Digital Multimeter (DMM) Operation
Document Number: 3700S
-900-01 Rev. A / August 2007 5-
15
AC voltage offset
The Series 3700, at 5½ digits resolution, will typically display 100 counts of offset on AC volts
with the input shorted. This offset is caused by the offset of the TRMS converter. This offset will
not affect reading accuracy and should not be zeroed out using the REL feature. The following
equation expresses how this offset (VOFFSET) is added to the signal input (V
IN
):
Example:
Range= 1VAC, Offset = 100 counts (1.0mV), Input = 100mV RMS
Therefore, the displayed reading is 0.100005V.
The offset is seen as the last digit, which is not displayed. Therefore, the offset is negligible. If
REL were used to zero the display, the 100 counts of offset would be subtracted from V
IN
,
resulting in an error of 100 counts in the displayed reading.
Current measurements (DCI and ACI)
The Series 3700 can make DCI measurements from 1pA to 3A and ACI measurements from
1mA to 3A RMS.
WARNING To prevent electric shock, never make or break connections while power
is present in the test circuit.
NOTE Also see crest factor information contained in AC voltage measurements and crest
factor (on page 5-9).
Amps measurement procedure
1. Press the OPENALL key to open all switching channels.
2. Select the amps measurement function by pressing the FUNC key until "DCI" or "ACI" (as
applicable) is displayed.
3. Use the RANGE ▲ and ▼keys to select a measurement range consistent with the
expected current, or press the AUTO key to select autoranging (AUTO annunciator turns
on).
4. Apply the current(s) to be measured.

Keithley 3720 Specifications

General

Brand	Keithley
Model	3720
Category	Multimeter
Language	English